Electromagnetic field detection systems and methods

ABSTRACT

A method and apparatus configured to detect electromagnetic field events are disclosed. One apparatus includes an antenna and a circuit electrically connected to the antenna. The circuit includes electronics communicatively connected to the antenna via a direct current isolation circuit and an equalizer compensating for the differentiating frequency response of the antenna. The circuit also includes a logarithmic amplifier electrically connected to the equalizer and configured to generate a range of signals based on signals received at the antenna. The circuit further includes a peak detector receiving signals from the equalizer and configured to capture a peak value of the signals. The electromagnetic field event is detected at least in part based on the peak signal value.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication No. 61/252,540, filed Oct. 16, 2009, and U.S. ProvisionalPatent Application No. 61/292,118, filed Jan. 4, 2010, the disclosuresof which are hereby incorporated by reference in their entireties.

TECHNICAL FIELD

The present disclosure relates to detection of electromagnetic fields.In particular, the present disclosure relates to both systems andmethods for electromagnetic field detection.

BACKGROUND

Exposure to electromagnetic fields can cause interference or damage toelectronic equipment, causing that equipment to malfunction or renderingit nonoperational. This is particularly a risk in the case of sensitivecomputing system data, which can be corrupted or lost in the event of astrong electromagnetic pulse or intentional electromagnetic interferenceevent (EMP/IEMI).

EMP/IEMI events typically take one of two forms. First, high fieldevents correspond to short-duration, high voltage events (e.g., up toand exceeding 100 kilovolts per meter), and typically are of the form ofshort pulses of narrow-band or distributed signals (e.g., in thefrequency range of 1 MHz to 10 GHz). These types of events typicallygenerate high voltage differences in equipment, leading to high inducedcurrents and burnout of electrical components. Second, low field events(e.g., events in the range of 0.01 to 10 volts per meter) areindications of changing electromagnetic environments below the highfield damaging environments, but still of interest in certainapplications.

Existing electromagnetic systems use electrical antennas to detect theexistence of a high-field or low-field event. For example, electricaldipole antennae, D dot detectors, or electro-optical detectors can beused. Electrical dipole antennae typically operate using a Schottky-typediode detector system, which receives signals directly based on theinduced voltage at the antenna. D dot detectors measure the time rate ofchange of electrical displacement, and deduce the electrical fieldstrength at an antenna by integrating the time rate of change of anelectrical field over a set amount of time. As such, these detectorsalso operate directly on the electrical field. Electro-optical detectorsuse changes of an index of refraction in a solid or liquid based on thepresence of an electromagnetic field.

These systems have drawbacks. This is because each of the above types ofantennas and associated circuitry either cannot respond to events acrossthe entire expected signal range of high field and low field events, oris too expensive or unreliable for use in certain environments. In thecase of a high field event (e.g., a high voltage pulse or other eventhaving a large signal intensity, as explained above), the variouselectrical antennae described above observe a large electrical field,resulting in a large induced voltage on the antenna. Additionally,common mode current flowing on the outer surface of an antenna probe orattached cable can cause unpredictable variations in the output power orvoltage produced by the antenna. This can cause potential damage todownstream circuitry. Even in the case of low field events, it can bedifficult to adequately capture events over the entire signal range ofexpected frequencies (e.g., 1 MHz to 10 GHz). Furthermore, it can bedifficult to manage a high voltage antenna configuration in theproximity to sensitive electronic equipment to be protected,particularly if that electronic equipment is intended to be shieldedfrom large electronic signals.

For these and other reasons, improvements are desirable.

SUMMARY

In accordance with the following disclosure, the above and other issuesare addressed by the following:

In a first aspect, an apparatus configured to detect electromagneticfield events is disclosed. The apparatus includes an antenna and acircuit electrically connected to the antenna. The circuit includes anequalizer communicatively connected to the antenna via a direct currentisolation circuit, the equalizer compensating for differentiatingfrequency response of the antenna. The circuit also includes alogarithmic amplifier electrically connected to the equalizer andconfigured to generate a range of signals based on signals received atthe antenna. The circuit further includes a peak detector receivingsignals from the equalizer and configured to capture a peak value of thesignals. The electromagnetic field event is detected at least in partbased on the peak value.

In a second aspect, a method of detecting high field electromagneticevents includes monitoring a magnetic field of an electromagnetic waveusing a shielded loop magnetic antenna. The method further includescapturing a peak signal value of an analog signal based on a magnitudeof the magnetic field at a peak detector communicatively connected tothe shielded loop magnetic antenna. The method also includes determiningthe existence of a high field electromagnetic event based at least inpart upon the captured peak signal value, wherein determining theexistence of the high field electromagnetic event includes inferring anelectrical field based on the measured magnetic field.

In a third aspect, an apparatus configured to detect high fieldelectromagnetic field events is disclosed. The apparatus includes afirst shielded loop magnetic antenna, a second shielded loop magneticantenna oriented in a direction normal to the first shielded loopmagnetic antenna, and a third shielded loop magnetic antenna oriented ina direction normal to the first and second shielded loop magneticantennas. The apparatus further includes a first circuit electricallyconnected to the first shielded loop magnetic antenna, the first circuitconfigured to capture a first peak value of signals received at thefirst shielded loop magnetic antenna. The apparatus also includes asecond circuit electrically connected to the second shielded loopmagnetic antenna, the second circuit configured to capture a second peakvalue of signals received at the second shielded loop magnetic antenna.The apparatus includes a third circuit electrically connected to thethird shielded loop magnetic antenna, the third circuit configured tocapture a third peak value of signals received at the third shieldedloop magnetic antenna. The apparatus also includes a processorconfigured to detect an electromagnetic field event based on the peakvalue detected at least in part based on the first peak value, thesecond peak value, and the third peak value.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example block schematic diagram of an electromagneticdetector system deployed at a facility;

FIG. 2 is an example system for detecting electromagnetic signals,according to a possible embodiment of the present disclosure;

FIG. 3A is an example antenna useable to detect high field pulses,according to a possible embodiment of the present disclosure;

FIG. 3B is an example antenna useable to detect high field pulses,according to a second possible embodiment of the present disclosure;

FIG. 4 is an example schematic block diagram of a circuit useable todetect high or low electromagnetic fields, according to a possibleembodiment of the present disclosure;

FIG. 5 is an example schematic block diagram of a circuit useable todetect high field electromagnetic fields, according to a furtherpossible embodiment of the present disclosure;

FIG. 6 is a schematic block diagram of a high field electromagneticpulse detection system including a high field detector apparatus,according to a possible embodiment of the present disclosure;

FIG. 7 is a schematic block diagram of a high field electromagneticpulse detection system incorporated into a shielded enclosure, accordingto a possible embodiment;

FIG. 8 is an example schematic depiction of an antenna structure useablein connection with the high field circuits discussed herein, accordingto a first possible embodiment;

FIG. 9 is an example schematic depiction of an antenna structure useablein connection with the high field circuits discussed herein, accordingto a second possible embodiment;

FIG. 10 is an example schematic depiction of an antenna structuremounted to an electromagnetically-shielded enclosure, according to apossible embodiment of the present disclosure;

FIG. 11 is a schematic block diagram of a low field electromagneticpulse detection system, according to a first possible embodiment of thepresent disclosure;

FIG. 12 is a schematic block diagram of a low field electromagneticpulse detection system, according to a second possible embodiment of thepresent disclosure;

FIG. 13 is a schematic block diagram of a low field electromagneticpulse detection system, according to a third possible embodiment of thepresent disclosure;

FIG. 14 is a schematic block diagram of a low field electromagneticpulse detection system, according to a fourth possible embodiment of thepresent disclosure;

FIG. 15 is a schematic block diagram of an electronic computing devicecapable of forming aspects of the present disclosure; and

FIG. 16 is a flowchart of methods and systems for detecting anelectromagnetic pulse event, according to a possible embodiment of thepresent disclosure.

DETAILED DESCRIPTION

Various embodiments of the present invention will be described in detailwith reference to the drawings, wherein like reference numeralsrepresent like parts and assemblies throughout the several views.Reference to various embodiments does not limit the scope of theinvention, which is limited only by the scope of the claims attachedhereto. Additionally, any examples set forth in this specification arenot intended to be limiting and merely set forth some of the manypossible embodiments for the claimed invention.

In general, the present disclosure relates to methods and systems fordetecting electromagnetic fields, and in particular types ofelectromagnetic fields that are capable of causing damage to electronicequipment. The present disclosure particularly involves detection andcapture of high field and low field EMP/IEMI events, to allow systems todetermine the type of event occurring and the particular state of theelectronic equipment at the time of the event. By combining certaincircuits and components with specifically designed enclosures anddetection equipment, damage from these types of electromagnetic eventscan be mitigated.

Specifically, certain aspects of the present disclosure relate toinferentially obtaining an estimated electrical field based on detectionof one or more magnetic fields, using a shielded magnetic loop antennaand associated circuitry. Additionally, specific circuits are disclosedthat have a fast rise time response and large dynamic range variation inamplitude, which allow those circuits to detect very narrow pulses ofvarious amplitudes, such as are generated during electromagnetic events,such as EMP/IEMI events.

The logical operations of certain aspects of the disclosure describedherein are implemented as: (1) a sequence of computer implemented steps,operations, or procedures running on a programmable circuit within acomputer, and/or (2) a sequence of computer implemented steps,operations, or procedures running on a programmable circuit within adirectory system, database, or compiler.

Referring now to FIG. 1, an example block schematic diagram of anelectromagnetic event detector system 100 deployed at a facility 102 isshown. The electromagnetic event detector system 100 includes aplurality of detectors 104 deployed throughout the facility 102. In theembodiment shown, the detectors 104 are deployed along a perimeter ofthe facility 102, as well as in association with electronic equipment106 within the facility. As such, the detectors 104 are configured tooperate across a variety of temperature ranges and in a variety ofweather conditions.

The detectors 104 can take any of a number of forms. In someembodiments, the detectors 104 can be a stand alone high field or lowfield electromagnetic event detector, as described herein. In suchembodiments, the detectors 104 can optionally also include othersensors, such as temperature, carbon monoxide, carbon dioxide, smoke,fire, radiation, or chemical sensors as well. Additionally, one or moredifferent types of detectors can be used at a single facility 102.

In the embodiment shown, each of the detectors 104 is communicativelyconnected to a detection system 108, which in various embodiments can bea centrally-located, shielded computing system configured to receivesignals from the detectors 104. The detection system 108 can analyze thesignals received from the detectors and, based on one or more differenttypes of calculations (as described below), can detect the presence of ahigh field or low field electromagnetic event, such as an EMP/IEMIevent. The detection system 108 can also communicate status informationregarding electromagnetic events, or observed electrical field readings,to a remote system (not shown) such as a data archival system or forpurposes of alarming to a remote monitoring system, or for forensicinformation.

Optionally, the detection system 108 also periodically determines thestate of various computing or electronic systems at the facility 102,such that, upon occurrence of an electromagnetic event, the last-knowngood status of that electrical or electronic equipment can be determinedand restored in case damage has occurred.

FIG. 2 provides additional details regarding an example system 200 fordetecting electromagnetic signals, according to a possible embodiment ofthe present disclosure. In the embodiment shown, the system 200 includesa number of detectors 202 interconnected with a central detector system204 by a network 206. In the embodiment shown, a number of detectors 202are associated with a single central detector system 204, which isgenerally a computing system configured to receive signals from thedetectors relating to peak values of electrical or magnetic signalsreceived at those detectors, and determine whether such valuescorrespond to an electromagnetic event, such as an EMP/IEMI event. Inalternative embodiments, each detector 202 can have a dedicatedmicroprocessor or computing system associated with it to detect ordetermine the existence of an electromagnetic event. Examplearrangements of detectors using such an arrangement are illustrated inFIGS. 6-7 and 13-14, described below. In such embodiments, thoseseparate microprocessors or computing systems can also communicate to anexternal system for example if centralized electromagnetic event loggingor management of detectors is desired.

The network 206 can take any of a number of forms. In some embodiments,the network 206 represents a secured communications network orpoint-to-point network using one or more electrical or fiber opticconduits between the detectors 202 and central detector system 204,using any of a number of standard communications protocols. In certainexamples, as described below, connection between a detector 202 andcentral detector system 204 can be accomplished using an RS-232electrical connection, or through use of fiber optic cabling (and any ofa variety of connectors and protocols). In still other embodiments, thedetectors 202 and central detector system 204 can communicate using anyof an umber of open networks and standards, such as the Internet. Otherembodiments are possible as well.

Using the system 200 to coordinate use of detectors 202 and a centraldetector system 204, it is possible to determine the direction fromwhich an electromagnetic event is detected, as well as the approximatedistance to that electromagnetic event. For example, a central detectorsystem 204 can compute an approximate location of the electromagneticevent based on the differing magnitudes and times at which electricalfields are observed at detectors spaced across a distance, if thelocations of those detectors are known, and normal attenuation of theelectrical field over free space is assumed.

Referring now to FIGS. 3A-14, additional details regarding specificelectromagnetic event detectors are described. The various exampledetectors and detector components are generally categorized into twotypes, representing high field detectors and low field detectors.Although it is recognized that one of these types of detectors isparticularly designed to sense and detect certain types ofelectromagnetic events, that detector may also be suitable to detectother events as well. For example, a high field detector may be useableto detect low field events as well, or vice versa.

Referring now to FIGS. 3A-10, various example circuits and components offield detectors are illustrated, as well as example implementationsusing such a detector. FIGS. 3A and 3B illustrates antennas 300, 320respectively, useable to detect high field pulses, according to apossible embodiment of the present disclosure. The antennas 300, 320are, in the embodiments shown, a shielded loop magnetic antenna. Forexample, in FIG. 3A, the antenna 300 is a generally circular loopantenna having a loop of approximately ¼ inch or less in diameter, andincluding shielding (e.g., a metal sheath); in FIG. 3B, the antenna 320is a generally rectangular loop antenna having size of approximately ¼inch in length. Each antenna includes shielding 302, 322 (represented bysolid lines) which extends around each loop 304, 324 (illustrated usingdotted lines), and effectively limits induction of an electrical fieldon the antenna, while making the loops 304, 324 susceptible to magneticfields. Each antenna also includes an exposed gap portion 306, 326,respectively, at which the magnetic field is induced. In particularembodiments, the antennas 300, 320 can be high field self integrating Bdot antennas. Other embodiments are possible as well.

In the embodiments shown, the antennas 300, 320 are configured to outputvoltages that are directly proportional to the electrical fieldamplitude that corresponds to the component of the observed magneticfield at a given frequency at the antenna. In certain embodiments, theantennas 300, 320 are configured to output voltages of zero to fivevolts, depending upon the field strength of the electrical fieldobserved (as inferred from the observed magnetic field strength).Preferably, the antennas 300, 320 have tailored inductance andresistance values to result in output of such voltages and has asufficiently fast (nanosecond range) response times to detect EMP/IEMIpulse events.

In certain embodiments, the antennas 300, 320 have output amplitudesthat in combination with an equalizer are independent of frequency, atleast over a predetermined frequency range. In certain embodiments, thatfrequency range can include about 200 MHz to about 10 GHz; in otherembodiments, the frequency range can extend from about 10 MHz to about10 GHz.

Additionally, although the antennas 300, 320 are described as beingapproximately ¼ inch in diameter, other sizes or dimensions of antennasare possible as well. By changing the size of the antennas 300, 320,different ranges of frequencies can be detected. The ¼ inch or lessantennas described herein are intended to be responsive across the rangeof frequencies in which EMP/IEMI events occur, as described in thepreceding paragraph.

In use, the antennas 300, 320 can each be used to obtain measurements offar field magnetic field measurements to infer electric field intensity,and therefore to detect electromagnetic pulses or other electromagneticevents, as previously described. When placed in a far field from theelectromagnetic radiation source (e.g., spaced such that a radiationsource is more than several wavelengths away from the antenna), themagnetic field strength detected by the antenna, H, is directlycorrelated to the electric field strength component Ē by the impedanceof free space, approximately 377Ω. This relationship can be representedby the following equation:H=Ē/377Ω

Using this relationship, a component of the electric field strength canbe inferred by measuring a directional magnetic field strength. Byvectorially adding such field strengths across all possible directions(e.g., using three antennas positioned normal to each other, asdescribed in FIGS. 5-10, below), an overall electrical field strengthcan be inferred.

Through use of the antennas 300, 320, electrical field strengths can beinferred for fields of very high intensity, including fields in therange of 100 volts per meter to 100,000 volts per meter withoutadditional attenuation of the inbound signal.

Referring now to FIG. 4, an example schematic block diagram of a circuit400 is shown that is useable to inferentially detect electromagneticfields, according to a possible embodiment of the present disclosure.The circuit 400, in the embodiment shown, is configured to be useable ineither high field detectors or low field detectors, such that use witheither a shielded loop magnetic antenna such as those shown in FIGS.3A-3B can detect high field electromagnetic events, or use with astandard electrical field sensing monopole or dipole antennas can detectlow field electromagnetic events. The circuit 400, in the embodimentshown, can therefore be used in a number of implementations ofelectromagnetic event detectors.

In the embodiment shown, the circuit 400 includes an antenna 402, whichcan, in various embodiments, represent a shielded loop magnetic antennaor other type of antenna, depending upon the particular intendedimplementation for the circuit 400. Leading from the antenna 402, adirect current circuit block 404 conditions the direct current portionof the signal received at the antenna, such that the detected portion ofthe received signal only represents the alternating current portion ofthe signal as induced by a field at the antenna (e.g., a magnetic fieldat a magnetic loop antenna in the case of high field event detection, oran electrical field at an electrical antenna in the case of low fieldevent detection).

An equalizer 406 connects to the direct current circuit block 404, andcompensates for the differentiating characteristics of the signalreceived at the antenna 402. A resistive attenuator circuit 408 scalesthe maximum expected antenna output threat voltage to a maximumallowable RF circuitry input voltage at a logarithmic detector 410,thereby preventing overload of the RF circuitry based on input signalsreceived by the antenna 402. For example, if the maximum allowable inputvoltage for the RF circuitry is 5.5 volts and the maximum expected inputvoltage is higher, the resistive attenuator circuit 408 is configured todivide down the voltage in linear proportion to ensure that the RFprocessing circuitry is not damaged by signals received at the antenna.

In the embodiment shown, the resistive attenuator circuit 408 splits theincoming signal into two paths, for lower level signals and higher levelsignals. The lower level signals are amplified when passed to thelogarithmic detector, to ensure that the signals received at thelogarithmic detector 410 are in a range where its response is mostlinear. In certain embodiments, to achieve a dynamic range of over about60 dB, separated, scaled signals are used that are in the approximately30-40 dB range.

The logarithmic detector 410 receives signals from the resistiveattenuator circuit 408, and provides a dynamic range of values to a peakdetector 412. Specifically, the logarithmic detector 410 demodulates anRF input signal and outputs a baseband voltage proportional to the logof the input power. In certain embodiments, the logarithmic detector canbe an ADL 5519 dual logarithmic detector, from Analog Devices, Inc. ofNorwood, Mass. Other logarithmic amplifies can include, for example, anAD8319 logarithmic amplified from Analog Devices, or a LT 5334 fromLinear Technologies of Milpitas, Calif. Other logarithmic amplifierscould be used as well, depending upon the particular timing and expectedsignals received by the detector at the antenna 402.

The multi-stage peak detector 412 captures peak values of signals outputfrom the logarithmic detector 410. Preferably, the peak detector has afast rise time (e.g., less than about 3 ns) sufficient to capture narrowpulse EMP/IEMI events, and a sufficiently long hold time to allow aslower periodic sampling of that peak value. In certain embodiments, therise time of the peak detector can detect signals as quickly asapproximately 3 nanoseconds, and can hold that signal value forapproximately 60 microseconds or longer (allowing kilohertz-levelsampling frequencies of the peak detector, despite the narrow nature ofEMP/IEMI events). In the embodiment shown, the peak detector 412 is atwo-stage peak detector; however, other designs of peak detectors arepossible as well. Additionally, in the embodiment shown, two peakdetectors 412 a-b are used, one for the higher-level signals and one forthe lower-level signals received at the logarithmic detector 410. Whenthe values captured by the peak detector 412 are obtained (e.g., by amicroprocessor, as described below), the higher of the scaled signals isselected for determining a value of the electrical field (or an inferredvalue of a component of the electrical field, in the case of a highfield detector arrangement).

A microprocessor 414 receives captured readings from the peak detector412 via one or more analog to digital converters 416 (illustrated asanalog to digital converters 416 a-b), which format the analog output ofthe peak detector for use by the microprocessor. Based on the observedsignal value captured by the peak detector, the microprocessor candetermine the existence of an electromagnetic event (e.g. an EMP/IEMIevent) according to any of a number of particular algorithms. In oneexample, the observed signal value is compared to a predetermined valuerepresenting harmful electromagnetic

The microprocessor 414 can perform a number of additional functions,beyond determination of electromagnetic events. For example, themicroprocessor can, in certain embodiments, generate alarms or othernotifications based on the determination of electromagnetic events. Themicroprocessor can also periodically store the state of one or moreother electronic systems, such that a last known good time of aparticular piece of electronic equipment can be known in the event ofdetection of an electromagnetic event, and can be logged alongside theexistence of that electromagnetic event. Additionally, other datalogging and security functions can be performed, and other sensor ordetector values can be captured and logged. Other sensors can include,for example, smoke or fire sensors, gas sensors, sound or light sensors,chemical sensors, or other types of sensors.

Referring to the circuit 400 overall, it is recognized the specificvalues used for resistors in the resistive attenuator circuit 408 canvary according to different embodiments of the present disclosure. Incertain embodiments, the range of monitored field strengths can beadjusted by changing the amount of attenuation provided by the resistiveattenuator circuit 408, thereby presenting a lower or higher inputvoltage to the logarithmic detector 410 and peak detector 412.

It is further recognized that the portion of the circuit 400 from thedirect current circuit block 404 to the peak detector(s) 412 can bereplicated as a standard block 418, to allow use with differentantennas, while using a common microprocessor for determining thepresent of an electromagnetic event. Examples in which such anarrangement is used are provided in connection with the high fielddesigns of FIGS. 6-7, described below.

FIG. 5 is an example schematic block diagram of a circuit 500 useable todetect high field electromagnetic fields, according to a furtherpossible embodiment of the present disclosure. The circuit 500represents a particular implementation of the circuit described above inconnection with FIG. 4, particularly suited to high field eventdetection.

In the embodiment shown, the circuit 500 includes an antenna 502, which,according to the various embodiments described herein relating to highfield detection, can be a shielded loop magnetic antenna. A balun 504performs signal conditioning on the received magnetic signals, andpasses those signals to an attenuator/limiter circuit 506. Theattenuator/limiter circuit 506 generally corresponds to the resistiveattenuator circuit 408 of FIG. 4, above. A logarithmic amplifier 508 andpeak detector 510 are analogous to those elements 410, 412 of FIG. 4 aswell.

A sample and clear circuit 512 can be included in the circuit 500 toread the signals captured by the peak detector 510. In certainembodiments, the sample and clear circuit 512 can include an analog todigital converter and programmable circuit, such as the A/D converter416 and microprocessor 414 of FIG. 4.

As recognized by comparing the portion of the circuit 500 from the balun504 through the sample and clear circuit 512, this generally correspondsto and would be useable interchangeably with the standard block 418 ofFIG. 4. In the embodiment shown, which is particularly used inassociation with high field events, the samples collected at the sampleand clear circuit 512 relate to inferred electrical field componentsfrom a magnetic field having a particular orientation.

To ensure that all directions are encompassed, two additional circuitsections and antennas can be used, with the antennas placed in anarrangement where each antenna is oriented normal to the orientation ofthe other two antennas, (e.g., forming a three-dimensional axis), inwhich a first antenna captures an “x” component of a magnetic field, asecond antenna captures a “y” component of the magnetic field, and athird antenna captures a “z” component of the magnetic field. Asillustrated, a microcontroller 514 collects sample readings from each ofthese circuit sections (i.e., respective sample and clear circuits 512associated with each oriented antenna), and infers an overall electricalfield strength based on the observed three components of the magneticfield. In particular, the total electrical field estimate can berepresented by the square root of the sum of squares of the directionalelectrical field estimates, as represented by the following equation:E _(T)=√{square root over (E _(x) ² +E _(y) ² +E _(z) ²)}

The value of E_(T) can be periodically transmitted to a remote systemfor further processing, or can be analyzed to determine the existence ofa high field electromagnetic event (e.g., an EMP/IEMI event). In analternative embodiment in which accurate electrical field amplitude isless critical than simply determining the existence of a pulse, simplysumming the constituent directional electrical fields can be performed.

Referring now to FIGS. 6-7, schematic block diagrams of high fieldelectromagnetic pulse detection systems are disclosed. The schematicblock diagrams illustrate example arrangements in which high fieldelectromagnetic pulse detection systems can be implemented, althoughothers are possible as well.

FIG. 6 illustrates a high field electromagnetic pulse detection system600 including a high field detector apparatus 602, which in theembodiment shown represents a stand-alone component. As such, the highfield detector apparatus 602 can correspond to a detector, such as thoseillustrated in FIGS. 1-2, above.

The high field electromagnetic pulse detection system 600 includes aplurality of shielded loop magnetic antennas. In the embodiment shown,the system 600 includes three shielded loop magnetic antenna 604 a-c,each oriented to capture magnetic signals along a different axis, suchthat each antenna 604 a-c is oriented normal to a plane formed by theother two antennas.

Signals from each of the antennas 604 a-c are fed into the high fielddetector apparatus 602, which includes three corresponding standardcircuit blocks 606. In various embodiments, the standard circuit blocks606 can correspond to the standard block 418 of FIG. 4, or correspondingblock of circuitry described in FIG. 5, above. The output of each of thestandard circuit blocks 606 is fed to a microprocessor 608 within thehigh field detector apparatus 602, which can determine the existence ofa high field event, log such events, or otherwise capture informationrelevant to the existence of such events (e.g., state information). Thehigh field detector apparatus 602 includes a communication interface 610which converts signals from the microprocessor 608 (e.g., RS-232formatted signals, or other differential or digital signals) andconverts those signals for communication external to the high fielddetector apparatus 602. In an example embodiment, the communicationinterface 610 converts the signals to fiber optic signals, andcommunicates with a complementary, remote communication interface 612via a fiber connection 614. To prevent interference by the highelectromagnetic event on the fiber connection 614, a waveguide beyondcutoff 616 can be included at the boundary of the housing of the highfield detector apparatus 602 to ensure that internal components of thatapparatus are not damaged. In such arrangements, the high field detectorapparatus 602 also has an electromagnetically shielded housing (e.g.,represented by the dotted line 602), preventing the high field eventfrom damaging the apparatus 602 itself. The high field detectorapparatus 602 also includes a maintenance block 618, which can providepower, backup battery, and power filtering functionality for thedetector apparatus 602.

From the remote communication interface 612, captured data relating tohigh field events can be communicated to a computing system 620, whichcan log or analyze those events, combine data relating to those eventswith data from other types of sensing systems, communicate that data toa central detector system via an Internet connection or other networkedconnection, or otherwise manage the collected data.

Referring to the high field electromagnetic pulse detection system 600overall, it is recognized that although a single high field detectorapparatus 602 and computing system 620 are illustrated, arrangements ofthe system are possible in which multiple high field detector apparatus602 could be associated with a single computing system, or multiplecomputing systems, depending upon the detection location requirementsand computing resources required to monitor those detectors.

FIG. 7 illustrates a high field electromagnetic pulse detection system700 that includes a high field detector 702 incorporated alongside ashielded enclosure 704. This arrangement may be particularly useful fordetector systems used at a facility when placed in close proximity tosensitive computing systems or other electronics (e.g., the detectorillustrated in FIG. 1 as associated with electronics at the facility102). In this embodiment, a plurality of antennas 706 a-c lead tostandard blocks 708, which generally correspond to antennas asillustrated in FIGS. 3A-3B, and blocks as described above with respectto FIG. 6. The high field detector 702 also includes a microprocessor710 analogous to the microprocessor 608 of FIG. 6, and a similarelectromagnetically shielded enclosure (represented by dotted line 702).

In comparison to the system 600 of FIG. 6, rather than including acommunication interface in this arrangement, the detector 702 is mounteddirectly to an enclosure 704, such that a computing system 712 can beplaced within an electromagnetically shielded enclosure or rack system,and can monitor the detector 702 as previously explained. In theembodiment shown, the detector 702 can be mounted to the enclosure byusing a radio frequency (RF) gasket 714 at a waveguide beyond cutoffopening in the enclosure to allow electrical communication between themicroprocessor 710 of the detector 702 and the computing system 712within the enclosure. The radio frequency gasket 714 is, in theembodiment shown, sized and positioned to prevent electromagneticsignals from penetrating the electromagnetically shielded enclosure pastthe waveguide beyond cutoff opening, which allows electricalcommunication into the enclosure 704.

In various embodiments, the electrical connection 716 between thesecomponents can be an RS-232 or RJ-45 style differential signalcommunicative connection. Additionally, as illustrated, power can becommunicated through the RF gasket 714 and into the detector 702, suchthat the detector need not include a contained maintenance block, asdisclosed in the system 600 of FIG. 6.

The enclosure 704 can be any of a number of styles ofelectromagnetically-shielding enclosures, and preferably shields fromhigh field events, such as those detected using the high field detector702. In various embodiments, the enclosure can be manufactured based onthe techniques and systems described in copending U.S. patentapplication Ser. No. 12/906,875, entitled “Modular ElectromagneticallyShielded Enclosure”, and filed on Oct. 18, 2010, the disclosure of whichis hereby incorporated by reference in its entirety.

Although in the embodiment shown the high field detector 702 is mountedexternally to the enclosure 704, in an alternative embodiment, theentire high field detector 702 and associated antennas 706 a-c can beplaced entirely within the enclosure 704, such that high field eventswould only be detected if the integrity of the enclosure itself is firstbreached. Other arrangements in which detectors are placed bothinternally and externally to the enclosure are possible as well.

As illustrated in the example detector arrangements of FIGS. 6-7, theuse of a simple, inexpensive circuit allows a user to createelectromagnetic event detection systems including redundant detectorsfor relatively low cost, and which can be used to detect electromagneticevents in various locations around a facility. Furthermore, although theantennas 604 a-c and 706 a-c of FIGS. 6-7 are exposed to high fieldevents, those antennas only generate relatively low electrical responsesto those fields, and can pass those low, “safe” signals to detectorcircuitry as described in connection with FIGS. 4-7.

Referring now to FIGS. 8-10, various structural arrangements of antennasand mechanical layouts for high field electromagnetic detection devicesare illustrated. FIG. 8 is an example schematic depiction of an antennastructure 800 useable in connection with the high field circuitsdiscussed herein, according to a first possible embodiment. In thisembodiment, three antennas 802 a-c are generally mounted on and extendfrom a pyramidal base 804. Each antenna 802 a-c is in this embodiment ashielded loop magnetic antenna, and is oriented in direction and suchthat the loop is oriented normal to the direction of each of the othertwo antennas, to ensure a three-dimensional capture of magnetic fieldsnear the antenna structure 800. Optionally, one or more circuits, suchas the standard module described in FIGS. 4-5, could be included in thebase 804 of the antenna structure 800, or an electrical connection canextend from the base 804 to such circuitry.

FIG. 9 illustrates a second example of an antenna structure 900 useablein connection with the high field circuits. In this embodiment, againthree shielded loop magnetic antennas 902 a-c are used, and each extendsalong an axis in a direction normal to the other two antennas, and has aloop that is oriented in a direction normal to the orientation of theother two loop antennas. The antennas 902 a-c are mounted in thisembodiment to a cubic or rectangular base 904, which can also houseeither one or more standard modules or other circuits for processingsignals received at the antennas, or forwarding those signals to suchcircuits for processing.

Now referring to FIG. 10, an example schematic depiction of the antennastructure 900 of FIG. 9 is illustrated as mounted to anelectromagnetically-shielded enclosure 1000 is shown. In thisembodiment, a gasket 1002 is located on a bottom side of the base 900adjoining the enclosure 1000, to provide electrical communicationthrough a waveguide-beyond-cutoff connection between circuitry in thebase (e.g., the circuitry disclosed as included within the detector 702of FIG. 7), and circuitry or computing systems within the enclosure 1000(e.g., a computing system such as system 712 of FIG. 7).

Although the antenna structure 900 of FIG. 9 is illustrated as mountedon the enclosure 1000, it is recognized that other antenna structures,such as structure 800 of FIG. 8 could be used in connection withmounting a detector external to an enclosure. Other arrangements ofantennas and antenna structures could be used as well.

Referring now to FIGS. 11-14, arrangements of devices and systems fordetecting low field events are illustrated, according to variousembodiments of the present disclosure. The embodiments illustrated inFIGS. 11-14 operate according to analogous principles to those of thehigh field event devices, but require less concern regarding shieldingof (1) output data from the detector, and (2) input signals from anantenna, at least because the expected signals to which such devices andsystems are exposed are not expected to cause immediate damage to thosesystems.

FIGS. 11-12 refer to arrangements in which a low field electromagneticdetector can be integrated with an existing communications module usedfor remote sensing. FIG. 11 is a schematic block diagram of a low fieldelectromagnetic pulse detection system 1100, according to a firstpossible embodiment. The system 1100 includes an antenna 1102interconnected to a low field detector device 1104. In the embodimentshown, the antenna can be an electrical antenna, such as a shortmonopole antenna, or other types of similar antennas. The detectordevice 1104 generally includes a single standard block 1106, which cancorrespond to the standard blocks disclosed in the circuits of FIGS.4-5, above.

As with the high field detector arrangements of FIGS. 4-7, the low fielddetector device 1104 includes a microprocessor 1108 communicativelyconnected to the standard block 1106, which is capable of capturing andstoring peak signal values for the electromagnetic field as observed atthe antenna 1102.

In the embodiment shown, the low field detector device 1104 alsoincludes a digital to analog converter 1110, which allows the device1104 to communicate the captured data from the microprocessor 1108 to anexternal module 1112 having an analog input data connection. In certainembodiments, the external module 1112 can be configurable to communicatewith remote computing systems via a network or Internet connection, orvia wireless connection. For example, the external module 1112 can be,in certain embodiments, a remote sensor monitoring and aggregationsystem, such as a Nose monitor module manufactured by PureChoice, Inc.of Burnsville, Minn. Other remote sensor monitoring and aggregationsystems are useable as well.

FIG. 12 is a schematic block diagram of a second example low fieldelectromagnetic pulse detection system 1200. The system 1200 generallyincludes an antenna 1102 interconnectable to a low field detector device1202. The low field detector device 1202 includes a standard circuitmodule 1106 and microprocessor 1108, as in the system 1100 of FIG. 11.However, in contrast to detector device 1104 of FIG. 11, the device 1202is configured to directly communicate with a digital external module1204. As such, in this embodiment no digital to analog converter isrequired, and the communicative connection to the digital externalmodule 1204 is also digital, rather than analog.

In both the arrangements of FIGS. 11 and 12, the communicativeconnection between the remote system (e.g., remote systems 1112, 1204)can also be configured to deliver power to the detector devices 1104,1202, respectively. However, in alternative embodiments, those devicescan be configured to include separate power connections, or can includecircuitry to provide battery power to the circuitry within the standardcircuit module 1106 and microprocessor 1108.

Referring now to FIGS. 13-14, additional arrangements of low fielddetection systems are illustrated in which the detector modules arearranged as a stand-alone system configured to communicate with a remotecomputing system, rather than using interconnection to an externalmodule. FIG. 13 is a schematic block diagram of a low fieldelectromagnetic pulse detection system 1300, which generally includes anantenna 1102 communicatively connected to a low field detector device1302. The low field detector device 1302 generally corresponds to thesame device 1202 of FIG. 12 (i.e., it also includes a standard circuitmodule 1106 and microprocessor 1108), but communicates to a remotecomputing system 1304 via a standardized communication connection 1306,which, in the embodiment shown, can be an RS-232 or RJ-45 twisted pairconnection. Other network connections are possible as well.

FIG. 14 is a schematic block diagram of a low field electromagneticpulse detection system 1400, according to a further possible embodiment.The low field electromagnetic pulse detection system 1400 includes anantenna 1102 communicatively connected to a low field detector device1402, which includes a standard circuit module 1106 and microprocessor1108, as well as a communication interface 1404. The communicationinterface 1404 is configured to convert communication signals between anelectrical format associated with the microprocessor 1108 (e.g., theRS-232 or RJ-45 twisted pair signaling described in connection with FIG.13) to signals of another media type (e.g., fiber optic signals). Inthis embodiment, the low field detector device 1402 also includes awaveguide beyond cutoff 1406 at a boundary of the low field detectordevice 1402, configured to filter extraneous signals on an associatedoptical fiber 1407 interconnecting the communication interface 1404 anda remote communication interface 1408, which is configured to provide acomplementary optical-to-electrical conversion for communication of thesignals to a remote computing systems 1410.

Referring to the low field detector arrangements of FIGS. 11-14 overall,it is recognized that each of these arrangements can also be used asstand-alone detectors or as integrated with one or more shieldedenclosures, as described above with respect to the high field detectorsof FIGS. 6-7. Additionally, use of the low-field detectors of FIGS.11-14 entirely within an enclosure will provide additional advantages,because detection of any low field event within an enclosure couldsignify that the enclosure's electromagnetic shielding has somehow beencompromised, and could signal that fact prior to exposure of any of theother electrical or electronic components within that enclosure to apotentially damaging high field event. For example, low field detectorscould be used to indicate that some seal has failed on an enclosure, orthat a door or other aperture to the enclosure remains ajar, or otheranalogous event has occurred. In some arrangements, a low field detectorcould be placed entirely within a shielded enclosure, and acomplementary low level electromagnetic emitter could be placed outsideof the enclosure. Upon breach of the shielded enclosure, the detectorwould determine the existence of the breach, due to the persistentelectromagnetic fields present external to the enclosure due to theemitter.

FIG. 15 is a block diagram illustrating example physical components ofan electronic computing device 1500, which can be used to execute thevarious operations described above, and provides an illustration offurther details regarding any of the computing systems described above.A computing device, such as electronic computing device 1500, typicallyincludes at least some form of computer-readable media. Computerreadable media can be any available media that can be accessed by theelectronic computing device 1500. By way of example, and not limitation,computer-readable media might comprise computer storage media andcommunication media.

As illustrated in the example of FIG. 15, electronic computing device1500 comprises a memory unit 1502. Memory unit 1502 is acomputer-readable data storage medium capable of storing data and/orinstructions. Memory unit 1502 may be a variety of different types ofcomputer-readable storage media including, but not limited to, dynamicrandom access memory (DRAM), double data rate synchronous dynamic randomaccess memory (DDR SDRAM), reduced latency DRAM, DDR2 SDRAM, DDR3 SDRAM,Rambus RAM, or other types of computer-readable storage media.

In addition, electronic computing device 1500 comprises a processingunit 1504. As mentioned above, a processing unit is a set of one or morephysical electronic integrated circuits that are capable of executinginstructions. In a first example, processing unit 1504 may executesoftware instructions that cause electronic computing device 1500 toprovide specific functionality. In this first example, processing unit1504 may be implemented as one or more processing cores and/or as one ormore separate microprocessors. For instance, in this first example,processing unit 1504 may be implemented as one or more Intel Core 2microprocessors. Processing unit 1504 may be capable of executinginstructions in an instruction set, such as the x86 instruction set, thePOWER instruction set, a RISC instruction set, the SPARC instructionset, the IA-64 instruction set, the MIPS instruction set, or anotherinstruction set. In a second example, processing unit 1504 may beimplemented as an ASIC that provides specific functionality. In a thirdexample, processing unit 1504 may provide specific functionality byusing an ASIC and by executing software instructions.

Electronic computing device 1500 also comprises a video interface 1506.Video interface 1506 enables electronic computing device 1500 to outputvideo information to a display device 1508. Display device 1508 may be avariety of different types of display devices. For instance, displaydevice 1508 may be a cathode-ray tube display, an LCD display panel, aplasma screen display panel, a touch-sensitive display panel, a LEDarray, or another type of display device.

In addition, electronic computing device 1500 includes a non-volatilestorage device 1510. Non-volatile storage device 1510 is acomputer-readable data storage medium that is capable of storing dataand/or instructions. Non-volatile storage device 1510 may be a varietyof different types of non-volatile storage devices. For example,non-volatile storage device 1510 may be one or more hard disk drives,magnetic tape drives, CD-ROM drives, DVD-ROM drives, Blu-Ray discdrives, or other types of non-volatile storage devices.

Electronic computing device 1500 also includes an external componentinterface 1512 that enables electronic computing device 1500 tocommunicate with external components. As illustrated in the example ofFIG. 15, external component interface 1512 enables electronic computingdevice 1500 to communicate with an input device 1514 and an externalstorage device 1516. In one implementation of electronic computingdevice 1500, external component interface 1512 is a Universal Serial Bus(USB) interface. In other implementations of electronic computing device1500, electronic computing device 1500 may include another type ofinterface that enables electronic computing device 1500 to communicatewith input devices and/or output devices. For instance, electroniccomputing device 1500 may include a PS/2 interface. Input device 1514may be a variety of different types of devices including, but notlimited to, keyboards, mice, trackballs, stylus input devices, touchpads, touch-sensitive display screens, or other types of input devices.External storage device 1516 may be a variety of different types ofcomputer-readable data storage media including magnetic tape, flashmemory modules, magnetic disk drives, optical disc drives, and othercomputer-readable data storage media.

In the context of the electronic computing device 1500, computer storagemedia includes volatile and nonvolatile, removable and non-removablemedia implemented in any method or technology for storage of informationsuch as computer readable instructions, data structures, program modulesor other data. Computer storage media includes, but is not limited to,various memory technologies listed above regarding memory unit 1502,non-volatile storage device 1510, or external storage device 1516, aswell as other RAM, ROM, EEPROM, flash memory or other memory technology,CD-ROM, digital versatile disks (DVD) or other optical storage, magneticcassettes, magnetic tape, magnetic disk storage or other magneticstorage devices, or any other medium that can be used to store thedesired information and that can be accessed by the electronic computingdevice 1500.

In addition, electronic computing device 1500 includes a networkinterface card 1518 that enables electronic computing device 1500 tosend data to and receive data from an electronic communication network.Network interface card 1518 may be a variety of different types ofnetwork interface. For example, network interface card 1518 may be anEthernet interface, a token-ring network interface, a fiber opticnetwork interface, a wireless network interface (e.g., WiFi, WiMax,etc.), or another type of network interface.

Electronic computing device 1500 also includes a communications medium1520. Communications medium 1520 facilitates communication among thevarious components of electronic computing device 1500. Communicationsmedium 1520 may comprise one or more different types of communicationsmedia including, but not limited to, a PCI bus, a PCI Express bus, anaccelerated graphics port (AGP) bus, an Infiniband interconnect, aserial Advanced Technology Attachment (ATA) interconnect, a parallel ATAinterconnect, a Fiber Channel interconnect, a USB bus, a Small ComputerSystem Interface (SCSI) interface, or another type of communicationsmedium.

Communication media, such as communications medium 1520, typicallyembodies computer-readable instructions, data structures, programmodules or other data in a modulated data signal such as a carrier waveor other transport mechanism and includes any information deliverymedia. The term “modulated data signal” refers to a signal that has oneor more of its characteristics set or changed in such a manner as toencode information in the signal. By way of example, and not limitation,communication media includes wired media such as a wired network ordirect-wired connection, and wireless media such as acoustic, RF,infrared, and other wireless media. Combinations of any of the aboveshould also be included within the scope of computer-readable media.Computer-readable media may also be referred to as computer programproduct.

Electronic computing device 1500 includes several computer-readable datastorage media (i.e., memory unit 1502, non-volatile storage device 1510,and external storage device 1516). Together, these computer-readablestorage media may constitute a single data storage system. As discussedabove, a data storage system is a set of one or more computer-readabledata storage mediums. This data storage system may store instructionsexecutable by processing unit 1504. Activities described in the abovedescription may result from the execution of the instructions stored onthis data storage system. Thus, when this description says that aparticular logical module performs a particular activity, such astatement may be interpreted to mean that instructions of the logicalmodule, when executed by processing unit 1504, cause electroniccomputing device 1500 to perform the activity. In other words, when thisdescription says that a particular logical module performs a particularactivity, a reader may interpret such a statement to mean that theinstructions configure electronic computing device 1500 such thatelectronic computing device 1500 performs the particular activity.

One of ordinary skill in the art will recognize that additionalcomponents, peripheral devices, communications interconnections andsimilar additional functionality may also be included within theelectronic computing device 1500 without departing from the spirit andscope of the present invention as recited within the attached claims.

FIG. 16 is a flowchart of methods and systems 1600 for detecting anelectromagnetic pulse event, according to a possible embodiment of thepresent disclosure. Generally, the methods and systems can be performedat least in part using (1) a standard circuit block, as describedherein, with respect to either low field or high field systems, and (2)a microprocessor or computing device communicatively connected to thestandard circuit block and configured to analyze peak values obtainedusing the circuit block, as described above.

In the embodiment shown, the methods and systems are instantiated at astart operation 1602, which corresponds to initial setup of one or moredetectors at a facility or other location to be monitored, as well asconnection of the one or more detectors to other computing devicesconfigured to coordinate detection and analysis of high field and/or lowfield electromagnetic events, such as EMP/IEMI events.

A field detection operation 1604 corresponds to detection of a field atan antenna that is interconnected with a standard block. As previouslydescribed, the field detection operation 1604 can correspond todetection of one or more directional components of a magnetic fieldusing one or more oriented shielded loop magnetic antennas, as describedabove in connection with high field detection systems in FIGS. 3A-3B andFIGS. 4-10. Alternatively, the field detection operation 1604 cancorrespond to detection of an electrical field using a short monopoleantenna, in the case of detection of a low field electromagnetic event,as described in connection with FIGS. 11-14.

An optional inferential operation 1606 infers an electrical field basedon the reading obtained by the field detection operation 1604. Theinferential operation 1606 will be performed in the case where ashielded loop magnetic antenna is used to detect a magnetic field, forexample in the case of a high field detection system.

An electromagnetic event determination operation 1608 determines whetheran electromagnetic event has occurred. Typically the electromagneticevent determination operation 1608 includes sampling a peak valuedetected using a standard circuit module and associated microprocessor,and performing one or more additional operations on that sample todetermine whether a high or low field event occurs. For example, in thecase of a high field event, the peak value may be summed or otherwisecombined with other inferred electrical field values (e.g., by using thesquare root of a sum of squares) to arrive at an overall electromagneticfield value, and comparing that value to a preset known threshold, overwhich it is assumed that a high field event has occurred. In a furtherexample, for low field events, the detected peak value can be directlycompared to a known threshold value, and based on that comparison theexistence of a low field event can be determined.

If no high or low field event is detected, operational flow can returnto the field detection operation 1604 to continue monitoring theelectrical and/or magnetic fields present at the detector. However, if ahigh or low field event is detected, operational flow proceeds to anevent communication operation 1610, which communicates the event (e.g.,including the field values and time at which the field values werecaptured) to either memory or a remote system for alarming or furtheranalysis. A storage operation 1612 corresponds to storing the fieldvalues and time, as well as information derived from those values orotherwise associated with the detector (e.g., the conclusion regardingwhether a high or low field event has occurred, status of one or moreelectrical or electronic systems associated with the detector, and othersensor information from other associated or interconnected sensors) at acomputing system remote from the detector. Operational flow can thencontinue to the field detection operation 1604, resulting in continuedmonitoring of the electrical and magnetic fields present at thedetector. An end operation 1614 corresponds to completed detection aftera desired (e.g. preset or undetermined) amount of time.

Referring to FIG. 16 generally, it is recognized that aspects of themethods and systems can be performed at a detector, while other aspectscan be performed at a remote computing system, such as a centralizeddetector management system (e.g. as illustrated above in connection withFIGS. 1-2).

Referring now to FIGS. 1-16 generally, it can be recognized that anumber of advantages are realized using the techniques for inferringelectrical fields and for detecting the existence of electromagneticevents as described herein. For example, using the shielded loopmagnetic antennas, standard circuit blocks, data processing components,and associated structures described herein, a low-cost, comprehensivemonitoring system can be constructed for protection of electricalequipment at any of a variety of facility types where data protection isa priority.

The above specification, examples and data provide a completedescription of the manufacture and use of the composition of theinvention. Since many embodiments of the invention can be made withoutdeparting from the spirit and scope of the invention, the inventionresides in the claims hereinafter appended.

The invention claimed is:
 1. An apparatus configured to detectelectromagnetic pulse (EMP) and intentional electromagnetic interference(IEMI) events, the apparatus comprising: a shielded loop magneticantenna configured to receive signals representing at least a portion ofa far field magnetic field generated from an electromagnetic pulse (EMP)or intentional electromagnetic interference (IEMI) event, the EMP orIEMI event having an electric field amplitude between 10 volts/meter and100,000 volts/meter and a frequency of between 1 MHz to 10 GHz; and acircuit electrically connected to the shielded loop magnetic antenna,the circuit including: an equalizer connected to the shielded loopmagnetic antenna via a direct current isolation circuit, the equalizeroutputting signals having amplitudes independent of frequencies ofdetected signals, the equalizer compensating for a varying frequencyresponse of the antenna; a logarithmic amplifier electrically connectedto the equalizer and configured to generate a range of signals based onsignals received at the antenna; a peak detector receiving signals fromthe logarithmic amplifier and configured to capture a peak value of thesignals; and wherein the peak detector determines a peak value of anelectrical field of the EMP or IEMI event based on the captured signals.2. The apparatus of claim 1, further comprising a microprocessorcommunicatively connected to the peak detector, the microprocessorprogrammed to calculate the existence of the electromagnetic fieldevent.
 3. The apparatus of claim 2, further comprising ananalog-to-digital converter connected between the peak detector and themicroprocessor, the analog-to-digital converter configured to generate adigital representation of the peak value, and wherein the microprocessorcalculates the existence of the electromagnetic field event based on thedigital representation of the peak value detected.
 4. The apparatus ofclaim 1, further comprising a second peak detector receiving signalsfrom the equalizer and detecting a second peak value of the signals. 5.The apparatus of claim 1, wherein the peak detector is a two-stage peakdetector.
 6. The apparatus of claim 1, further comprising a resistiveattenuator connected between the equalizer and the logarithmicamplifier.
 7. The apparatus of claim 1, wherein the circuit is furtherconfigured to sample the peak value periodically to determine theexistence of the EMP or IEMI event.
 8. The apparatus of claim 1, whereinthe shielded loop magnetic antenna has a diameter of ¼ inch or less. 9.The apparatus of claim 1, further comprising: a second shielded loopmagnetic antenna oriented in a direction normal to the shielded loopmagnetic antenna; a second circuit electrically connected to the secondshielded loop magnetic antenna, the second circuit configured to receivea second peak value of the signals; a third shielded loop magneticantenna oriented in a direction normal to the shielded loop magneticantenna and the second shielded loop magnetic antenna; a third circuitelectrically connected to the third shielded loop magnetic antenna, thethird circuit configured to receive a third peak value of the signals;wherein the electromagnetic field event is detected at least in partbased on the peak value, the second peak value, and the third peakvalue.
 10. The apparatus of claim 9, wherein the EMP or IEMI event isdetected based on a comparison of a threshold value to a vector sum ofmagnitudes of the peak value, the second peak value, and the third peakvalue.
 11. A method of detecting high field electromagnetic pulse (EMP)and intentional electromagnetic interference (IEMI) events, the methodcomprising: monitoring a magnetic field of an electromagnetic wave usinga shielded loop magnetic antenna configured to receive signalsrepresenting at least a portion of a far field magnetic field of theelectromagnetic wave, the electromagnetic wave having an electric fieldamplitude between 10 volts/meter and 100,000 volts/meter and a frequencyof between 1 MHz to 10 GHz; capturing a peak signal value of an analogsignal representing a magnitude of the magnetic field at a peak detectorthat is connected to the shielded loop magnetic antenna; and determiningthe existence of a high field electromagnetic pulse (EMP) or intentionalelectromagnetic interference (IEMI) event based at least in part uponthe captured peak signal value, wherein determining the existence of thehigh field EMP or IEMI event includes determining an electrical fieldbased on the magnetic field.
 12. The method of claim 11, furthercomprising communicating data relating to the high field EMP or IEMIevent to a computing system.
 13. The method of claim 11, furthercomprising periodically reading the peak signal value of the peakdetector and clearing the peak signal value from the peak detector. 14.The method of claim 11, further comprising combining the peak signalvalue with a second peak signal value and a third peak signal value toarrive at a combined signal magnitude.
 15. The method of claim 14,wherein the combined signal value represents a square root of the sum ofsquares of the peak signal value, the second peak signal value, and thethird peak signal value.
 16. An apparatus configured to detect highfield electromagnetic pulse (EMP) and intentional electromagneticinterference (IEMI) events, the apparatus comprising: a first shieldedloop magnetic antenna; a second shielded loop magnetic antenna orientedin a direction normal to the first shielded loop magnetic antenna; athird shielded loop magnetic antenna oriented in a direction normal tothe first and second shielded loop magnetic antennas; wherein each ofthe first, second, and third shielded loop magnetic antennas areconfigured to receive signals representing at least a portion of a farfield magnetic field of an electromagnetic wave, the electromagneticwave having an electric field amplitude between 10 volts/meter and100,000 volts/meter and a frequency of between 1 MHz to 10 GHz; a firstcircuit electrically connected to the first shielded loop magneticantenna, the first circuit configured to detect a first peak value ofsignals received at the first shielded loop magnetic antenna; a secondcircuit electrically connected to the second shielded loop magneticantenna, the second circuit configured to detect a second peak value ofsignals received at the second shielded loop magnetic antenna; a thirdcircuit electrically connected to the third shielded loop magneticantenna, the third circuit configured to detect a third peak value ofsignals received at the third shielded loop magnetic antenna; and aprocessor configured to detect an electromagnetic pulse (EMP) orintentional electromagnetic interference (IEMI) event based on the peakvalue detected at least in part based on the first peak value, thesecond peak value, and the third peak value.
 17. The apparatus of claim16, wherein the first circuit, the second circuit, and the third circuiteach further include: a direct current isolation circuit electricallyconnected to the antenna; an equalizer electrically connected to thedirect current isolation circuit, the equalizer compensating for avarying frequency response of the antenna; a logarithmic amplifierelectrically connected to the equalizer; and a peak detectorelectrically connected to the logarithmic amplifier.
 18. The apparatusof claim 16, wherein the processor is programmed to detect theelectromagnetic pulse (EMP) or intentional electromagnetic interference(IEMI) event based on a square root of the sum of squares of the peaksignal value, the second peak signal value, and the third peak signalvalue.